Proton-deuteron correlation functions from pionless effective field theory

High-energy collisions of nucleons or nuclei provide fascinating insights into the nature of the strong interaction. Interestingly, not only can one learn from such processes about quantum chromodynamics (QCD) under extreme conditions, but also about the nuclear interaction at much lower energies, by measuring correlations among hadrons that are produced in the collision. Recently, experiments have advanced to study three-body systems in this way, going beyond just two-hadron correlations. A solid understanding of the theory governing the process is crucial to use measurements in order to constrain nuclear and other hadronic interactions.

This contribution presents such a theoretical study for the proton-deuteron (pd) correlation function, calculated in Pionless effective field theory (Pionless EFT) using a formalism that fully accounts for the underlying three-body dynamics in the system. Pionless EFT is designed to capture the universal low-energy features of few-nucleon systems that arise from the fact that the two-nucleon scattering lengths are unnaturally large, and it has been used to make a number of predictions for low-energy few-nucleon processes. In particular, the systematic inclusion of electromagnetic corrections, relevant for studying the pd system, is well understood within Pionless EFT. In this work, the formalism is extended to calculate the pd correlation function up to next-to-leading order in the EFT expansion.